Water is injected into oil reservoirs to improve the recovery of oil when easily mobilized oil becomes depleted. Known as waterflooding, this is an important secondary recovery technique (Hyne, N J 2001, “Non-technical guide to petroleum geology, exploration, drilling, and production”, 2nd edition, Pen Well Corp., Tulsa, Okla., USA). Oil and water are incompatible phases, thus a number of techniques have been studied in an effort to decrease the repellency between the oil and water phases, thereby improving oil mobilization and recovery during waterflooding. U.S. Pat. No. 4,463,806 describes the use of synthetic surface-active agents, wherein said agents are injected into a subterranean formation in an effort to improve oil recovery. Synthetic agents are expensive and must be brought to the oil well site for use.
Some microbial products can decrease oil-water repellency because they are surface active. Only certain groups of microorganisms are able to produce these surface-active compounds (Neu, T. R (Microbiological Reviews, 1996, 60:151-166). Such biologically produced surface-active compounds have also been suggested for use in oil recovery. Many biologically produced surface-active compounds are based on production by pure cultures of aerobic microorganisms (for example, U.S. Pat. No. 4,522,261). Biological production of surface-active agents by stimulation of microorganisms within the oil reservoir has also been reported (for example, WO1989010463), however it is difficult to control and monitor production of surface-active compounds in remote, underground oil formations.
Surface-active agents are also useful for the remediation of shallow, subsurface sites that have been contaminated with hydrocarbons. The introduction of surface-active agents can be used to solubilize or mobilize hydrocarbons adsorbed to soil particles or present as a separate hydrocarbon phase (see, for example, West, C C and Harwell, J H, “Surfactants and Subsurface Remediation” Environ. Sci. Techncl., 1992, 26(12):2324).
There exists a need for an inexpensive and effective method for producing surface-active agents that can be used for improved hydrocarbon-water compatibility.